xfs_repair: allow '/' in attribute names

xfs_repair: allow '/' in attribute names

For some reason, since the earliest days of XFS, a '/' character
in an extended attribute name has been treated as corruption by
xfs_repair.  This despite nothing in other userspace tools or the
kernel having this restriction.

My best guess is that this was an unintentional leftover from
common code between dirs & attrs in the "da" code, and there has
never been a good reason for it.

Since userspace and kernelspace allow such a name to be set,
listed, and read, it seems wrong to flag it as corruption.
So, make this test conditional on whether we're validating a name
in a dir, as opposed to the name of an attr.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>